1. Field of the Invention
The present invention relates to a supporting column and a cassette using the same, and more particularly to a supporting column for use in transporting substrates.
2. Description of the Related Art
In handing substrates, such as glass substrates for LCDs, cassettes are useful for holding or stowing the substrates to keep them from contacting, and thus damaging each other. In general, cassettes comprise a box-shaped resin frame equipped with pairs of supporting columns, each column having a plurality of slots. The slots are so arranged such that a group of slots in a same horizontal plane cooperate with each other to stow one substrate. Thus, a plurality of substrates can be safely stacked within a cassette, one above the other.
A supporting column 10 of a conventional cassette described in JP Yodogawa Kasei publication number H04-139741 and shown in FIG. 6, comprises a resin-made rod 11 and a metal rod 13. The metal rod 13 is located in a through hole 115 defined in the center of the resin-made rod 11. Moreover, the resin-made rod 11 is provide with a plurality of annular slots 111 defined in the resin-made rod 11, and defines a fixing slot 113 and a threaded hole 131 in each of two opposite ends.
A plurality of the supporting columns 10 are fixed to a frame (not shown) to form a cassette (not shown) by means of the fixing slot 113 and a screw (not shown). But in use, only a small portion of the surface of each annular slot 111 actually touches the surface of a substrate. Furthermore the material making up the resin-made rod 11 must resist high temperatures and have high durability. Therefore, this circular-shape design of circle shape wastes material and is more expensive than necessary.
For the above reason, an improved supporting column with a low manufacturing cost is desired.